A pilot-scale hybrid process of ozone and biological aerated filters( BAF) with the capacity of 36 ~ 120 t / d was applied for advanced treatment of the secondary biologically effluent from a dyeing and tannery park wastewater treatment plant. Ozone pretreatment was optimized,then the effect of pollutants removal perform-ance with ozone and different medias BAF was investigated. The results showed that the best treatment efficiency and economical conditions were ozone dosage of 25 mg / L,three dosing points of 6 ∶ 3 ∶ 1 and contact time of 42 min; the effluent COD and color of ozone-biological activated carbon( O 3-BAC) were stabled at 50 mg / L and 5 times under the best conditions. The effluent met the first level B criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant( GB18918-2002). The effluent of ozone-composite BAF just met the first level B criteria specified,but neither COD nor color in the effluent of ozone-ceramist BAF can meet the first level B criteria specified.

A pilot-scale hybrid process of ozone and biological aerated filters (BAF) with the capacity of 36 t x d(-1) was applied for advanced treatment of the secondary biologically effluent from a dyeing and tannery park wastewater treatment plant. The pollutants removal performance along the height of different medias BAFs were investigated. The results showed that the average COD and color were 55.4 mg x L(-1) and 12.6 times at the height of 1500 mm in activated carbon BAF, and were 55.6 mg x L(-1) and 9.4 times at the height of 1 800 mm in composite BAF, both of the effluent at each height met the first level B criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB 18918-2002). Along the height of ceramist BAF, the COD and color were seldom removed. In activated carbon BAF and composite BAF, COD and ammonia nitrogen were both greatly decreased at the height of 1 200 mm, then decreased slowly. The biomasses simultaneously reached the maximum at the height of 900 mm in activated carbon, composite and ceramist BAF, with the maxims of 30.69, 28.87 and 15.94 nmol x g(-1), respectively.

The combined process of ozone and biological aerated filter(BAF) was used to treat secondary biologically treated effluent from a tannery park wastewater treatment plant.The running performances of BAFs with different media were investigated during the biofilm growth period.The pollutants removal performance and mechanisms of BAFs with different media at ozone dosage of 25 mg/L were explored.Three BAFs operating in parallel were filled with activated carbon,ceramsite and mixture of activated carbon and ceramsite with 1 ∶ 1 volume ratio.The COD removal rates of BAF with activated carbon and BAF with the mixture first decreased,then increased and finally stabilized during the biofilm growth period.After 32 d,the effluent COD was below 60 mg/L in both reactors.The COD removal efficiency of the ceramsite BAF was not significant.During the steady state operation of the activated carbon BAF,the average COD and color were decreased from 117 mg/L and 112.5 times in the influent to 50 mg/L and 6 times in the effluent,which met the first level B criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002).In the same period,biomasses in the activated carbon,mixture and ceramsite BAFs were 30.69 nmol/g,25.87 nmol/g and 15.18 nmol/g respectively.

The effluent from a tannery wastewater biotreatment plant was treated by the ozone oxidation-activated carbon biofilter process.Under the conditions of ozone dosage 25 mg/L,oxidation time 25 min and biofilter HRT 1 h,the average COD,TOC,UV254(absorbance at 254 nm with 1 cm of optical path) and mass concentration of ammonia nitrogen in the treated wastewater are 51 mg/L,15.1 mg/L,0.12 and 0.51 mg/L,respectively.The treated wastewater quality can meet the B level in the first grade of National Discharge Standards for Municipal Wastewater Treatment Plant(GB18918-2002).

A hybrid process of acidification-CASS was applied for the treatment of tannery park wastewater.The results showed that the average COD and ammonia nitrogen decreased from 607 mg·L-1 and 50.7 mg·L-1 in raw water to 70 mg·L-1 and 5 mg·L-1 in treated effluent with the average removal rates as high as 88.5% and 90.1%.The effluent quality met the first grade in the national wastewater integrated standard(GB 8978-1996).

Ferric-carbon microelectrolysis treatment processes were applied for advanced treatment of biologically treated effluent of tannery wastewater in an industrial park.Priority of impact factors and their optimal conditions were studied with an orthogonal experiment and a single impact factor experiment.The results show that the priority of impact factors for ferric-carbon microelectrolysis treatment processes is Fe/C ratio>reaction time>pH.The self-made ferric-carbon(Fe/C=3/1)and the purchased ferric-carbon granule products decrease the average CODCr from 116 mg/L to 45 mg/L and 50 mg/L,respectively,under the condition of 1.5 h of reaction duration and pH 5.Treated water both meet the B level in first grade of the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918—2002).Running cost for self-made ferric-carbon is 0.28 yuan/t.

A pilot-scale hybrid process of ozone/biological activated carbon(O3/BAC) with a capacity of 36 m3/d was applied for advanced treatment of secondary biological effluent from a dyeing and tannery park wastewater treatment plant.The pollutant removal performance was investigated at different ozone dosages,and the removal mechanism was discussed.The results showed that the optimal removal efficiencies of COD,color,TOC and UV254 were reached using ozone dosage of 25 mg/L,with the removal rates of 17.4%,54.3%,14.7% and 47.5%,respectively.During biofilm growth period,COD removal rate first decreased,then increased and finally stabilized at 50% after 32 d.When the BAC filter reached a stable period,the average COD and color were decreased from 100 mg/L and 112.5 times in the influent to 50 mg/L and 5 times in the effluent,and the wastewater quality met the first level B criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002).The micromolecular organics degraded from macromolecular organics by ozone were absorbed and oxidized by BAC,meanwhile,some extracellular polymeric substances and metabolites were produced.The proportions of TOC and UV254 were increased from 60.7% and 58.8% in the influent to 66.8% and 65.7% in the effluent at the molecular weight of less than 1 ku.

Concentrations,pollution sources and distribution characteristics of heavy metals(Cr,Zn,Cu,Ni,Pb,Cd,Fe,Mn) were investigated in the influent,effluent and activated sludge of a tannery and textile dyeing industrial park wastewater treatment plant in Zhejiang,based on which the influence of heavy metals on the pollutant removal performance was discussed.Results showed that the highest contents of heavy metals in the influent were Cr and Fe,respectively reaching 16.40 mg/L and 15.80 mg/L.These heavy metals accumulated in the activated sludge,with Cr and Fe as high as 12550 mg/kg-dried sludge and 13671 mg/kg-dried sludge.The enrichment of heavy metals in the activated sludge not only brought difficulties in the sludge disposal and resource utilization,but also gave negative impact on the solid-liquid separation of sludge and the pollutants removal performance.

Fenton oxidation was applied for advanced treatment of bio-treated tannery wastewater.The results showed: the influential factors of Fenton oxidation process,from weak to strong,were H2O2 dosage,Fe2+ concentration,pH,and reaction time in order.When the influent mean CODCr concentration was 116.6 mg/L,under the optimized operation condition of H2O2 dosage 50 mmol/L,Fe2+ dosage 10 mmol/L,pH 3,and reaction time 60 minutes,the mean CODCr in effluent was 31.7 mg/L,while under the operation condition of H2O2 dosage 25 mmol/L,Fe2+ dosage 7.5 mmol/L,pH 5,and reaction time 40 minutes,the mean CODCr in effluent was 46.6 mg/L.In economical operation condition with optimized operation cost ratio,the operation cost could be saved by 2.3 Yuan/m3.